In the production of drinks, such as fruit juices, nectar and still drinks (non carbonated soft drinks) and the like, the intention is often to mix two or more flows with one another. The different flows often are of different character and, for example, may consist of juice concentrate which is mixed with water or sugar solution which is mixed with fruit juice, etc. In order to ensure that the desired mixture is obtained, the sugar content is measured after the mixing operation. The sugar content is measured in °Brix with the aid of a refractometer. In order that the Brix value of the product be as reliable as possible, the mixture must be as homogeneous as possible before the product reaches the refractometer.
In most countries, juices and nectars have a statutory minimum Brix content in order to be sold under each respective name. If there is an insufficient mixture and, as a result, an unreliable Brix value in the subsequent measurement, it must be ensured that there is a margin to the lowest permitted Brix value, which involves increased raw materials costs.
The mixing operation may be put into effect in different ways. A previously common method is to batchwise mix in a tank with an agitator. This method is both costly and takes up considerable space. Another method is to carry out the mixing operation in a so-called static mixer where the two flows are caused to pass through an apparatus with a number of inclined plates or panels. These give rise to turbulence in the flows, which results in a mixture of the different flows. However, this method has proved not to be entirely reliable when there are major differences in viscosity in the flows.
Two further similar methods are described in Patent Specifications SE 508 137 and SE 0103591-4. These methods are completely continuous and entail that a smaller flow is led into a larger flow in such a manner that both of the flows are counter-directed. These methods give a good mixture, but for certain practical applications higher demands are placed, such as, for example, the mixing of juice concentrate with fibres, where there is a risk that the fibres fasten in narrow parts of the apparatuses. A number of practical applications also place extremely high demands on hygiene which must be met, at the same time as the intention is to realise as thorough a mixing as possible.